雪中γ-六六六的直接光降解及其影响因素

The Photodegradation of γ-HCH in Snow and the Influence Factors

通过室内模拟实验,以高压汞灯为光源,研究了γ-六六六(γ-HCH)在雪中的光转化规律,建立了γ-HCH光转化的一级反应动力学方程,考查了γ-HCH光转化的影响因素及反应机理。结果表明,在紫外光作用下,雪中γ-HCH可以发生光转化反应,光转化反应符合一级动力学方程。酸性条件抑制光转化,随酸性的增强抑制作用增强;碱性条件促进光转化。H2O2抑制γ-HCH的光转化,随H2O2浓度增加,抑制作用先减弱后增强。NO-3和Fe3+抑制光转化,抑制作用随浓度增大而增强。HCO-3对光转化的作用不明显。γ-HCH降解产物为四氯环己烯、五氯环己烯、一氯酚、三氯酚,其机理为氯化氢或氯原子的脱除以及羟基自由基的取代。

Through the indoor simulation experiment, using high pressure mercury lamp as the light source, the photochemical reaction of γ-HCH in snow is investigated, established the first order kinetics equation, and examined the influence factors including hydrogen peroxide. The results show that, under UV light, γ-HCH could be photoconverted in snow, and the photochemical reaction obeyed the first order kinetics equation. H2O2 inhibited the photochemical reaction of γ-HCH, and with the increasing concentration of H2O2, the inhibition effect of H2O2in-creased at first and then decreased. Acidic conditions inhabited the photochemical reaction, and the inhibition effect increased with the decreasing of pH value. Alkaline conditions promoted the photochemical reaction. N03 inhibited the photochemical reaction, and the inhibition effect increased with the increasing concentration of NO3-. Different concentration of HCO3 all had no effect on the photoconversion of γ-HCH. Fe3＋ inhibited the photochemical reaction, and the inhibition effect increased with the increasing concentration of Fe3＋ The photoconversion products were tetrachlorocyclohexene, pentachlorocyclohexene, chlorophenol, trichlorophenol, and the photoconverision mechanisms are the removal of chlorine atoms or hydrogen chloride and the substitution of hydroxyl radical.